Vehicles include a power plant, such as an internal combustion engine, that generates drive torque. The drive torque is transferred from the engine and through a transmission to drive wheels and to propel the vehicle along a surface. A vehicle speed is monitored, is displayed to the vehicle operator and is used by a control system to regulate vehicle and/or power plant operation.
Some vehicles include a transmission output shaft speed (TOSS) sensor that monitors a rotational speed of the transmission output shaft. The vehicle speed is determined based on the TOSS. The TOSS sensor is responsive to a toothed wheel that is fixed for rotation with the transmission output shaft. More specifically, the TOSS sensor is responsive to the rising and falling edges of the teeth of the toothed wheel, and generates a signal indicating the rate at which the teeth pass the TOSS sensor.
In some vehicles, the transmission output shaft vibrates while the vehicle is stopped or is traveling slowly and the power plant (e.g., the engine) is revved. For example, if the transmission is in a neutral state and the power plant is revved, vibration of the transmission output shaft can result. In some cases, a rising or falling edge of a tooth can be positioned just under the TOSS sensor. If the transmission output shaft sufficiently vibrates, a false or otherwise inaccurate TOSS sensor signal can result.